Anti-howling Circuit: by changing the audio frequency of the guitar pickup channel, suppress the howling of the resonant horn, so as to adapt to the installation and debugging of types of guitars. USB Charging Interface: the charging interface on the pickup panel is convenient, simple and universal. Audio digital Effect: built-in high-speed high-fidelity audio digital module, configuring high-quality circuit to realize reverberation, the extension of sound effects such as chorus and delay, making the sound more flexible, transparent, broad and beautiful. BT Playback Circuit: which can connect the guitar to the audio signal of the BT device, and then play guitar accompaniment music or songs through the guitar itself or speakers, or download all kinds of audio files and play with the guitar through the Internet platform. Mounting Hole: 12mm The product is designed to enhance the guitar playing experience with advanced features such as an anti-howling circuit, USB charging interface, and built-in audio digital effects. It allows for seamless connectivity with Bluetooth devices for playback and offers a convenient mounting hole for easy installation. Color: Black Material: Plastic + Electronics Package Contents: 1*Guitar Pickup(without 1*18650 battery) Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.